Exhaust systems receive exhaust gas generated as a product of combustion carried out in cylinders in internal combustion engines. The exhaust systems may include exhaust manifolds which receive exhaust gas from individual cylinders in the engine and merge the exhaust gas flow into a single exhaust passage. The intake manifold may be positioned external to a cylinder head in the engine or integrated into the cylinder head. Due to packaging constraints the exhaust manifolds as well as other exhaust conduits in the exhaust system may include a number of bends, curves, etc., which may increase back pressure and generate noise, vibration, and harshness (NVH) in the exhaust system.
US 2009/0007552 discloses an exhaust manifold including tubes enclosed by a housing defining an interior section of the exhaust manifold. The inventors have recognized several drawbacks with the exhaust manifold disclosed in US 2009/0007552. For instance, the exhaust manifold disclosed in US 2009/0007552 is bulky, which increases the profile of the exhaust system. Moreover, the exhaust manifold disclosed in US 2009/0007552 also generates a large amount of NVH which may only be partially attenuated by the interaction between the tubes and the interior region. As a result, customer dissatisfaction is increased. Further, it will be appreciated that other exhaust manifold designs may involve tradeoffs between compactness, noise attenuation, and back pressure generation.
The inventors herein have recognized the above issues and developed an exhaust system in an engine. The exhaust system includes an exhaust manifold include at least one exhaust runner having an inlet and a flow rotation element including at least one vane, the flow rotation element positioned in the inlet of the exhaust runner swirling exhaust airflow entering the exhaust runner.
The flow rotation element decreases flow separation and turbulence in the exhaust gas flow through the exhaust manifold, thereby reducing impingement and noise generated in the exhaust manifold. As a result, NVH within the exhaust system is decreased and customer satisfaction is increased.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure. Additionally, the above issues have been recognized by the inventors herein, and are not admitted to be known.